Day 1: Assuming you made it to Hawaii the same way I did you traveled here by plane so check into your hotel and relax after a long journey from the mainland for the first hour because the next 35 are going to be the time of your life. To start off your incredible trip, go to the Maui Ocean Center and Aquarium. It's a really cool experience and a blast. It's full of native fish of Hawaii and its natural ocean predators as well a great learning experience. After your aquarium experience make sure you go to the beautiful beaches of Maui. There isn't a bad one and the water is incredible!
Day 2: After your nice long rest and the adjustment to the time change day 2 should be a more adventurous day. I would recommend a waterfall hike. There are some amazing hikes and even some with waterfalls that you can jump off of and swim in the crystal clear water. This is usually an all day adventure as you have to travel inland and find the best places to go. Once you get back from you adventure, sunburned and weary it's a great time to grab a bite to eat at one of the local fish shops and take your dinner down to the beach and watch the sunset.
Day 3: After your long day of hiking and swimming it's a day to relax and let your guide to the driving. Today you are going to want to take the Road to Hana. There are amazing stops and sights along the way such as the seven falls and the black sand beach, (but don't take the sand because its said to be cursed). When you finally make it to Hana after approximately 600 turns and numerous one land bridges you will be transported to a different time and place. Hana is an extremely small town with only a small store, local restaurant that serves basic food like sandwiches, salads and burgers and a bank that is only open for a few hours a day. Hawaii in general is a very laid back place to visit and Hana is even more laid back!
Day 4: After your relaxing, stomach testing drive to Hana today you are going to go snorkeling! The place to do that is Molokini. There are numerous snorkeling companies that you can sign up with and I would recommend one that has a good reputation. Molokini is a small sunken crater that is home to a vast majority of marine life. There are numerous different fish species, sea turtles, eels, and even reef sharks if you're lucky! After a trip to Molokini to see the marine life you will want to go back again and again. If you're lucky on the way back to the marina (and if you are in Hawaii at the right time of the year) you may even get lucky enough to see whales.
Day 5: Most flights departing from Hawaii back to the mainland have an evening flight so you are able to go shopping in Lahaina. Lahaina is a small town but it is a heavily populated area. There is great shopping, fun things to do and even Banyan Tree Park located at one end of town. This tree is HUGE! It encompasses a whole park (almost a whole block) and provides a wonderful backdrop for a great family picture. Pack your bags and head to the airport, just don't forget to declare all those pineapples you are bringing back with you!!